Functionalizing surfaces by implantation of active, functional particles is an area of interest to a number of fields. By functionalizing surfaces with particles, users may create surfaces that present the useful properties of the particles, such as antimicrobial properties and biosensing.
One area where functionalized surfaces is of particular interest is the reduction of microbial contamination. It is estimated that microbial contamination costs billions of dollars in equipment damage, product contamination, energy losses, and medical infections each year. As one example of the magnitude of this problem, microbial-related damage to buildings and building materials is estimated at several billions of dollars each year.
Microbial contamination also causes significant illness and attendant loss of productivity. Commonly used devices such as phones, automatic teller machines (ATMs), and computer keyboards characteristically present microbial densities many times greater than the microbial densities present on toilet seats and other similar fixtures.
Interest in functional surfaces is not limited to antimicrobial surfaces. As one example, surfaces having the ability to bind to specific biological molecules are also of interest.
Plastics also typically contain a variety of additives—such as plasticizers and lubricants—to help achieve certain desired properties. These additives also, however, provide the carbon needed to sustain the growth and proliferation of microbes. Hence, while plastics typically require one or more additives to achieve a particular characteristic, such additive-laden plastics may also be susceptible to microbial contamination.
At present, substrate-particle composites that include particles of various functionalities are made by two methods. In the common bulk incorporation method of production, particles are non-specifically dispersed throughout the entirety of a substrate. In common coating processes, particles are dispersed within a secondary coating layer that is then disposed atop the main substrate or even atop additional primer or binder layers.
These methods, however, pose certain disadvantages. Bulk incorporation is inefficient in that while the goal of the method is to produce a substrate having particles on the surface, a large number of particles are also dispersed within the substrate. Thus, in bulk incorporation, a large number of particles are effectively buried within the substrate and can not be presented to the environment exterior to the substrate. As a result, a comparatively large number of particles are needed to functionalize the surfaces of a given substrate by way of bulk incorporation. Also, achieving uniform dispersion of particles within the substrate is difficult, but may nevertheless be necessary for uniform surface area coverage of the particles.
Coating processes also present certain inefficiencies. Use of a coating process to make a functionalized surface can involve multiple additional manufacturing steps, including surface pretreatment, priming, and curing. Second, the coating layer must sufficiently adhere or bind to the underlying substrate so as to avoid detachment from the substrate, which is especially challenging for polymer substrates. Proper execution of coating-based techniques may require significant research and development commitments, and may also require additional primer layers or surface treatments. Third, the coating layer must sufficiently entrap particles in order to prevent particles from loosening and escaping under use conditions.
Accordingly, there is a need in the art for composite structures having surface-borne particles that are securely and efficiently attached to the surfaces. The value of such structures would be enhanced if the structures presented such particles on the surface and the structures did not include unnecessary particles within that were not available to presentation to the environment exterior to the structure. There are also parallel needs for fabricating such structures and for other related devices.